1. Technical Field
The field of this invention is biopolymeric arrays.
2. Background of the Invention
xe2x80x9cBiochipsxe2x80x9d or arrays of binding agents, such as oligonucleotides and peptides, have become an increasingly important tool in the biotechnology industry and related fields. These binding agent arrays, in which a plurality of binding agents are deposited onto a solid support surface in the form of an array or pattern, find use in a variety of applications, including gene expression analysis, drug screening, nucleic acid sequencing, mutation analysis, and the like.
Such arrays may be prepared in a number of different ways. For example, DNA arrays may be prepared manually by spotting DNA onto the surface of a substrate with a micro pipette. See Khrapko et al., DNA Sequence (1991) 1:375-388. Alternatively, the dot-blot approach, as well as the derivative slot-blot approach, may be employed in which vacuum manifold transfers aqueous DNA samples from a plurality of wells to a substrate surface.
In yet another method of producing arrays of biopolymeric molecules, a pin is dipped into a fluid sample and then contacted with the substrate surface. By using a plurality or array of pins, one can transfer a plurality of samples to the substrate surface at the same time. Although such methods are efficient, they are not completely satisfactory. For example, depending the particular technique used to deposit the fluid sample, e.g. when the pin is contacted with the substrate surface, one can obtain spots of deposited fluid that have an irregular shape, spots that have a doughnut shape, or other undesirable configurations. Further disadvantages may include a lack of reproducibility.
Alternatively, an array of capillaries can be used to produce biopolymeric arrays. See WO 95/35505. Although the use of capillaries has certain advantages over other methods, problems with spot doughnut-like shape and spot homogeneity or spot reproducibility may be encountered. Specifically, present methods may result in the production of a spot with a doughnut-like shape.
In yet another method of producing biopolymeric arrays, arrays of biopolymeric agents are xe2x80x9cgrownxe2x80x9d on the surface of a substrate in discreet regions. See e.g. U.S. Pat. No. 5,143,854 and Fodor et al., Science (1991) 251:767-773. While effective in producing arrays, such methods are complicated as a plurality of synthesis steps are required. Furthermore, the achievable length of the grown biopolymer agent is limited.
Accordingly, there is continued interest in new methods of producing biopolymeric arrays, as well as devices for use therein. Ideally, such new methods and devices should produce arrays in which the biopolymeric spots have a substantially uniform and reproducible configuration. Furthermore, the methods should be simple, require few distinct steps and be adaptable to an automated format.
Patents and patent applications describing arrays of biopolymeric compounds and methods for their fabrication include: 5,242,974; 5,384,261; 5,405,783; 5,412,087; 5,429,807; 5,436,327; 5,445,934; 5,472,672; 5,527,681; 5,529,756; 5,545,531; 5,554,501; 5,556,752; 5,561,071; 5,599,895; 5,624,711; 5,639,603; 5,658,734; WO 93/17126; WO 95/11995; WO 95/35505; EP 742 287; and EP 799 897.
Other references of interest include: Lockhart et al., Nature Biotechnology (1996) 14: 1675-1680; Shena et al., Science (1995) 270: 467-470; Schena et al., Proc. Nat""l Acad. Sci. USA (1996)93:10614-10619; Shalon et al., Genome Res. (1996) 6: 639-645; Milosavljevic et al., Genome Res. (1996) 6:132-141; Nguyen et al., Genomics (1995)29: 207-216; Pixc3xa8tu et al., Genome Res. (1996) 6: 492-503; Zhao et al., Gene (1995) 166:207213; Chalifour et al., Anal. Biochem. (1994) 216:299-304; Heller et al., Proc. Nat""l Acad. Sci. USA (1997) 94: 2150-2155; Khrapko et al., DNA Sequence (1991) 1:375-388; Lehrach et al., Hybridization Fingerprinting in Genome Mapping and Sequencing, Genome Analysis, Vol. 1 (Davies and Tilgham, eds)(Cold Spring Harbor Press) (1990) pp 39-81; and Schena, M., BioAssays (1996) 18: 427-431.
Applicator devices for depositing a fluid sample on the surface of a substrate, as well as methods for their use, are provided. The subject applicator devices are elongate in shape and have a first end and a second end. The first end is substantially planar with a circular shape. Arising from the surface of the first end is a conical protuberance. The second end of the elongate device may have a means for attaching to an automated movement means. In using the subject devices, the first end is introduced into a fluid sample and then contacted with a substrate surface, whereby a volume of the fluid sample is deposited on the substrate surface. The subject devices and methods find use in a variety of applications, particularly in the preparation of biopolymeric arrays, such as nucleic acid and protein arrays.